The present invention is drawn to a self-propelled trailer for any purpose having a tongue jack which includes a support wheel which is powered by any suitable means. The preferred embodiment of the invention is a trailer which includes means for heating asphalt and a self-propelled tongue jack.
The prior art describes several types of devices used in coupling and uncoupling trailers. U.S. Pat. No. 5,451,076 to Burkhead discloses a pneumatic landing gear to raise and lower the feet of a trailer eliminating the need for a hand crank. Here, the gear incorporates the use of a pneumatic actuator which is powered by air from already existing air pressure in the trailer. The gear can be installed during the manufacturer of the trailer or as an add-on to an already existing trailer.
A device to align a trailer to the tow bar of a towing vehicle is described in Knisley, U.S. Pat. No. 5,338,047. The device has a wheeled body for easy rotation and alignment of the trailer tongue.
Morrison, U.S. Pat. No. 4,779,889, discloses a swivel wheel for a trailer. The wheel assembly has a goose-necked shaped axle and is capable of being mounted on a variety of trailer frames. The invention allows for a pivot means for easy movement of the trailer and a locking means to prevent any unwanted pivoting.
A drive mechanism for trailer lifting gear is described in Busby, U.S. Pat. No. 4,345,779. The trailer lifting gear has two telescopic support legs, an air driven rotary drive, and a connecting means. The telescopic support legs are generally wheeled to ease in movement of the trailer. The air driven rotary drive can be connected to a currently existing source of air pressure on the trailer.
United Kingdom Patent No. GB 2 223 465 A to Flounders discloses an articulated vehicle which has a tractor and a trailer. The trailer has a wheeled front end support which can be raised and lowered by a direct current electric motor. The invention is intended to eliminate the use of a hand crank to raise and lower the trailer for attachment and detachment.
The prior art also describes various processes for heating surfaces, including asphalt. A process for continuously heating an asphalt surface is described in Wiley et al., U.S. Pat. No. 5,653,552. The process involves moving at least two independent heaters arranged in a series back and forth along the asphalt surface until the asphalt is heated to the desired temperature. In addition, the process may involve rupturing the heated asphalt to establish a ruptured upper surface. After moisture is eliminated through mixing of the ruptured upper surface, the surface is pressed to provide a recycled asphalt surface.
U.S. Pat. No. 5,218,952 to Neufeldt describes a radiant heating apparatus used to heat a large surface area of asphalt to a desired temperature. The heating apparatus uses a pressurized gaseous fuel, such as propane, to generate heat and has an open bottom, covered with a layer of ceramic fiber between two layers of mesh and an upper chamber.
O""Brien, U.S. Pat. No. 5,188,481, discloses an asphalt heating unit which heats already existing asphalt surfaces. The heating unit rests on a movable frame which allows rotation of the heating unit to several positions. One embodiment of the invention substitutes a trailer for the movable frame. In addition, the heating unit may use various forms of heating sources in its heating chamber, such as an infrared heater.
U.S. Pat. No. 5,114,284 to Keizer et al. is a continuation of U.S. Pat. No. 4,749,303 to Keizer et al. The applications disclose a hinged asphalt heater. The heater has two heating sections with a hinge in the middle. Both sections contain wheels to allow the sections to be moved along the surface to be heated. The outer casing of the first section contains a removable fuel tank and the outer casing of the second section contains a set a trailer tires and a trailer tongue. The hinge allows the sections to be folded together so that the wheels of the second section are touching the ground and the trailer tongue can be attached to a vehicle for the easy movement of the heater. Each section has a mixing channel which receives a combustible fuel mixture for heating the section.
A gas pilot igniter for igniting combustible gases and burning fuel/air mixtures is described in London, U.S. Pat. No. 4,946,384. One advantage of the igniter is its ability to allow the use of fuels with variable combustion points. Here, the igniter includes a fuel gas inlet means, a primary mixing chamber, a main combustion chamber, a pre-combustion chamber and a baffle plate.
U.S. Pat. No. 3,852,025 to Placek discloses an infra-red heater. The heater is gas-fired and has a cup shaped body, an open front end and a mixing area for the combustible air mixture. A combustion screen is used to prevent flashbacks which are common in gas-fired radiant heat generators. In addition, the heater is particularly useful in the removal of paint, the softening of adhesives and the softening of flooring surfaces.
None of the above references, taken alone or in any combination, describe the trailer including self-propelled tongue jack disclosed and claimed herein.
A major problem encountered when using trailers of any sort is accurately positioning the trailer in the desired location or maneuvering the trailer through an area of restricted access. If the trailer and its contents are sufficiently light, the trailer can be moved manually (literally) or manually with the assistance of a wheeled trailer dolly. However, if the trailer and its load are sufficiently heavy (e.g., a large boat trailer or a trailer used in a semi-tractor/trailer rig), they cannot be moved manually. In most instances, the only means to move the trailer is to use a towing vehicle such as a car, truck, or tractor. As anyone who has tried to back a trailer-borne boat or mobile home into a garage can attest, it is not an easy task to maneuver the towing vehicle in reverse such that the trailer arrives at the desired location. Such efforts are invariably accompanied by much trial and error. In the course of such efforts, it is not uncommon that the trailer is mistakenly collided into surrounding structures or people, causing damage to both the item which was hit and the content being carried on the trailer.
A particular variation of the above-noted problems is encountered when using trailer-borne asphalt heaters. As amply illustrated in the references cited in the Description of the Prior Art, asphalt heaters often include a heating element which can be extremely heavy. For example, if refractory stone is used in the asphalt heating apparatus, it is not uncommon for trailers carrying such heaters to have gross weights exceeding 1,500 kg. However, during any given project, the trailer bearing the asphalt heater must be accurately positioned and repositioned as the job progresses. The large weight of such trailer-borne asphalt heating devices precludes positioning them by hand; a towing vehicle must be used to position the asphalt heater. As noted above, this makes it quite difficult to accurately position the heater without a good deal of trial and error.
The fact that a towing vehicle must be used in asphalt heating operations is doubly troublesome because not only must the asphalt heater be positioned accurately (in an often cluttered setting, such as an existing residential worksite), the task is complicated by the presence of softened asphalt. Due to existing structures, the towing vehicle must often be driven upon newly laid, still-malleable asphalt in order to access certain parts of the worksite. Due to the weight of the trailer, it tends to leave tire tracks in the still-warm asphalt. To eliminate the tracks, the asphalt must be re-heated (if necessary) and re-rolled. The only other alternative is to wait until the section of asphalt which must be traversed is sufficiently hardened and then proceed with the job. In either event, time (and therefore money) is wasted.
The present invention solves both problems by providing a trailer which is self-propelled via a powered tongue jack and which optionally includes a light-weight, high-efficiency asphalt heater. The trailer is moved long distances, such as to and from worksites, using a towing vehicle, in conventional fashion. When at the workplace (or storage site), the tongue jack described herein is lowered to support the trailer in a generally horizontal position, and, by virtue of a powered jack wheel, can be used to position the trailer, easily, quietly, and confidently, in either the forward or reverse direction. The jack is powered by any conventional means, including an ac or dc electric motor or an internal combustion engine. A reversible, variable-speed, dc electric motor powered by a conventional 12 Volt battery supply is preferred.
When using the powered jack, the user generally faces toward the rear of the trailer, in the direction the trailer is traveling. A 360-degree rotatable collar allows the trailer to be accurately positioned and re-positioned without the use of a towing vehicle. When the jack is powered using the preferred dc motor, operation of the jack is extremely quiet as compared to using a towing vehicle or an internal combustion engine.
It is preferred that the motor is controlled using a variable-speed, reversible trigger switch. Such switches are commonly used in hand tools such as power drills and the like. The variable-speed function of the switch and motor allows the trailer to be moved relatively quickly where there is no danger of collision, and then moved continuously slower where greater precision is required. Likewise, because the switch is reversible, the trailer can be moved back and forth to maneuver it into otherwise inaccessible locations.
The jack itself comprises a suitably rigid, essentially vertical member which serves to leverage the trailer into a horizontal position by contact with the ground. A wheel is positioned at the end of the vertical member to make contact with the ground. The wheel may be set on a fixed axle or may be castored to allow easy lateral movement. The vertical member may comprise a series of telescoping poles so that the jack can be raised clear of the ground when the trailer is attached to a towing vehicle. The vertical member itself may also be rotatably mounted to the trailer so that it can be moved from a first, engaged position, supporting the trailer, to a second, disengaged position, where the jack is moved up and away from the ground so as not to interfere with the towing of the trailer.
Another novel aspect of the invention is the combination of a self-propelled jack with a very straightforward, light-weight, and efficient asphalt heater. According to the invention, the asphalt heater comprises a housing which is divided into an upper chamber and a lower chamber by a sheet or board of permeable refractory material suspended within the housing. The lower chamber of the housing is open at its lower end. A fuel-air mixture is supplied to the upper chamber by means of a fuel supply line passing first through a venturi device (to mix the fuel with a proper proportion of air) and then into a supply manifold. The fuel is charged into the upper chamber at a relatively low pressure, preferably 0.10 to 0.50 inches of water (3.6xc3x9710xe2x88x923 to 1.8xc3x9710xe2x88x922 pounds per square inch, 2.54 to 12.7 kgs per m2).
The fuel-air mixture diffuses through the refractory material into the lower chamber of the housing, where it is ignited by an ignition sub-assembly. The burning fuel-air mixture creates a partial vacuum in the lower chamber of the housing, thereby encouraging movement of the fuel air mixture into the lower chamber. The refractory material functions to direct the heat of the combustion downward and out of the open end of the lower chamber. In use, the heat is directed against asphalt to soften it for various operations, such as printing of decorative designs and the like.
Further aims, objects, and advantages of the invention will become clear upon a complete reading of the Detailed Description of the Invention and attached drawing figures.